Apparatus for closing vacuum vessels



M. URICH APPARATUS FOR CLOSING VACUUM VESSELS Feb. 11, 1930.

Fiied June 28. 1924 Patented Feb. 11, 1930 MORITZ URIGH, OF BADEN, SWITZERLAND, ASSIGNOR T AKTIENGESELLSCHAFT BROWN, BOVERI AND 0111,

OF BADEN, SWITZERLAND APPARATUS FOR CLOSING VACUUM VESSELS Application filed June 28, 192 Serial No. 723,068, and in Germany July 16, 1923.

Various devices are known for closing vacuum vessels, of the type wherein two intercommunicating air spaces, for instance the two limbs of a U-tube are shut off from each 5 other by mercury or other sealing fluid. The

known constructions of this type are operated by lifting and lowering a vessel containing mercury, so that in the lifting movement the mercury passes into the two intercommunication spaces, and shuts off the communication between the two, whereas in the lowering movement the mercury flows back again, and the communication is reestablished. For this purpose however a-considerable height of lift of the mercury vessel is necessary in cases where a considerable difference in pressure is liable to occur between the two spaces after these latter have been shut off from each other. The height of the lift must generally be at least equal to, and in some constructions be at least one half of the height of the mercury column that is sup ported by the greatest occurring difference in pressure between the vacuum and the outer atmosphere. The necessity for this great lift renders the manipulation of such devices clifficult so that their use has hitherto been limited practically to laboratories.

The present invention now allows of providing a mercury closure by means of a much smaller range of movement of a much less heavy body. This is achieved by constructing the partition between the two intercommunicating air spaces in the form of a movable bell, so that the closure is effected by immersing the said bell into a quantity of mercury that is substantially at rest.

The improved apparatus according to this invention is illustrated by way of example in the accompanying drawings in which:

Figure 1 illustrates one modification, and

Figure 2 illustrates a second modification of the improved apparatus.

In the first modification illustrated in Figure 1; a and b are two concentric tubes; 0 is the bell-shaped partition by which the space between the tubes a and b is divided into two parts.

The tube a can be connected to the vacuum vessel at d, and the tube 6 can be connected to the air-pump at e. The two walls of the two tubes a and b are connected at their lower ends by the'mercury vessel f. When the hell 0 clips into the mercury, as in the position shown, the connection between d and e is interrupted, whereas when the hell 0 is lifted so that it does not dip into the mercury, the said connection is re-established.

If, after the shutting-off of the communication, a pressure higher than that in the vacuum vessel should occur in the space outside the bell 0, the mercury will rise in the space between a and c, and will fall in the vessel f. The length of the tube a above the level of mercury in the vessel f must therefore be at least equal to the height of the mercury column that can be supported by the greatest pressure-difference that can occur between the pressures at cl and e. The bellshaped partitions 0 must therefore be made at least of this length. On the contrary, by suitably dimensioning the cross sections of the free space between a and 0 and of the vessel f, the fall of the mercury level in f, and consequently the requisite height of lift of the partition 0 can be kept within any desired narrow limits.

The dipping and the lifting of the bell into and out of the mercury is effected most simply by electromagnetic means. In the example illustrated in Figure l the hell 0 is connected to a solenoid core 9 which is lifted by the action of the solenoid winding h located outside the vacuum duct. When this solenoid receives current the bell is lifted, and the bell falls again when the current is cut off from the solenoid it.

When the improved closing apparatus is included in a pipe between a vacuum vessel as m and a suitable air pump shown diagrammatically at a, driven by a suitable electric motor 0, the current in the solenoid h is made dependent in a known manner upon the voltage at the pump motor 0. The improved apparatus is thus closed when the working closing apparatus from being opened before the space between it and the pump has been sufliciently emptied of its air, it has been proposed in the case of similar devices, to employ a time relay by which the solenoid that effects the opening of the closing device, shall receive current a little time later than the motor of the air pump. In this case however the length of the delay is fixed once for all. The said length may be suiiicient perhaps if the vacuum in the connecting pipe has become reduced only a little, but under certain conditions it may fail if through any accident the full atmospheric pressure has penetrated into this connecting pipe. Moreover the simplicity of the entire apparatus will gain by the suppression of the said time relay. This is rendered possible in the improved apparatus according to the present invention by arranging that the lifting of the bell out of the mercury, instead of being effected by the attraction of the solenoid, is effected by the action of the buoyancy of a float attached to the bell, whilst an opposing force is produced outside the bell.

Figure 2 illustrates a constructional example hereof.

The parts a 72 and (Z correspond to the similar partsa, b and Z of Figure 1. In this construction the closing bell c is provided with a float 2' whose buoyancy is made such-that the bell c floats when it is in the position shown, whilst the float 2 itself is therefore completely submerged. The bell c is formed above the level of the mercury with apertures by which connection is established between the air spaces inside and outside the bell. g is again a solenoid core which is actuated by the current flowing in the solenoid h. The core is however not attached to the bell 0 in this construction.

The manner of the operation of this improved apparatus is as follows:

If the solenoid it loses its current, the solenoid core 9 falls and by its weight forces the hell 0 downwards until the apertures 10 are closed by the mercury. If now the vacuum in the space located outside the bell should become considerably reduced, the mercury will rise in the narrow space between a and 0, and will fall to a corresponding, but much smaller amount in the wide space between 6 and 0. At the same time by reason of the increased air pressure outside the bell 0 the force with which this bell is pressed downwards is still further increased. If now the solenoid g be lifted again, the bell 0 will not yet rise again, because it is kept down by the outer air pressure. Only, when by reason of the resumption of working by the pump the pressure in the space outside the bell is diminished to such an extent that it can be overcome by the buoyancy of the float connected to the bell, the bell will rise, and the apertures lo. will rise out of the mercury so that connection is re-established between the two spaces inside and outside the bell.

If for instance the bell 0 has a diameter of 25 mm. and a thickness of wall of 0.5 mm. at the point where it dips in the mercury (namely at the apertures 70), a higher external pressure of 1 mm. of mercury will be sufiicient to cause it to dip 30 mm. deeper below the line representing the position of equilibrium shown in the figure.

Only when the pressure outside the bell c has dropped to less than 1 mm. of mercury, the bell 0 will be able to rise. It the improved apparatus is employed, for instance, for clos-' ing a rectifier vessel against the air pump duct, then the improved apparatus can be opened quite safely at an external excess pressure of 1 mm. of mercury, because since the rectifier vessel has a much greater volume than the connecting duct between the closing member and the air pump, the pressure in the rectifier vessel can rise to only a small fraction of 1 mm. of mercury.

hat I claim is 1. An automatic seal for a vacuum vessel comprising a chamber iaving a port leading to said vessel and a port leading to an exterior space against which said vessel is to be sealedya sealing liquid in said chamber, an inverted tubular bell interposed between said ports and having its lower open end sealed in said liquid, said bell having floats tending to lift said bell for breaking its seal with the liquid under predetermned pressure difference conditions between said ports, an increase of the pressure at the port leading to the exterior space causing a displacement of the sealing liquid to produce a barometric column adjacent the walls of said bell of a hei ht corresponding to said pressure increase, said displacement of theliquid causing a decrease of the lifting power of said floats.

2. An automatic high-vacuum valve for vacuum vessels comprising a hermetically closed chamber, a tube leading from said vessel into said chamber from near the bottom thereof, an inverted tubular bell movably enclosing said tube, a sealing liquid in the bottom of said chamber, and a pipe connection from the space within said chamber outside said bell to the exterior space against which said vacuum is to be sealed, the weight of said bell tending to be innnersed in said liquid for establishlng a seal between said vessel and said exterior space, said bell having float means to lift the same from said liquid and break said seal, occurrence of a pressure increase in' said exterior space causing said liquid to be displaced to form a barometric column in the space between the interengaging portions of said tube and said bell to establish a seal around said tube, said displacement of the liquid resulting in a decrease of the lifting power of said float means, the height of the interengaging portions of said tube and bell, and the quantity, density and level of said sealing liquid being such as to form a barometric column of a height corresponding to the maximum pressure increase that may occur in said exterior space.

3. An automatic high-vacuum valve for vacuum vessels comprising a hermetically closed chamber, a tube leading from said vessel into said chamber from near the bottom thereof, an inverted tubular bell movably enclosing said tube, a sealing liquid in the bottom of said chamber, a pipe connection from the space within said chamber outside said bell to the exterior space against which said vacuum is to be sealed, the weight of said bell tending to be immersed in said liquid for establishing a seal between said vessel and said exterior space, said bell having float means to lift the same from said liquid and break said seal, occurrence of a pressure increase in said exterior space causing said liquid to be displaced to form a barometric column in the space between the interengaging portions of said tube and said bell to establish a seal around said tube, said displacement of the liquid resulting in a decrease of the lifting power of said float means, the height of the interengaging portions of said tube and bell, and the quantity, density and level of said sealing liquid being such as to form a barometric column of a height corresponding to the maximum pressure increase that may ocour in said exterior space, and externally actuated means for determinedly controlling the movement of said bell.

4. An automatic high-vacuum valve for vacuum Vessels comprising a hermetically closed chamber, a tube leading from said vessel into said chamber from near the bottom I thereof, an inverted tubular bell movably enclosing said tube, a sealing liquid in the bottom of said chamber, a pipe connection from the space within said chamber outside said bell to the exterior space against which said vacuum is to be sealed, the weight of said bell tending to be immersed in said liquid for establishing a seal between said vessel and said exterior space, said bell having float means to lift the same from said liquid and I break said seal, occurrence of a pressure increase in said exterior space causing said liquid to be displaced to form a barometric column in the space between the interengaging portions of said tube and said bell to establish a seal around said tube, said displacement of the liquid resulting in a decrease of the lifting power of said float means, the height of the interengaging portions of said tube and bell, and the quantity, density and level of said sealing liquid being such as to form a barometric column of a height corresponding to the maximum pressure increase that may occur in said exterior space, and electromagnetic means for controlling the movement of said bell.

5. A liquid seal for a vacuum vessel com prising a partition interposed between the vacuum vessel and a pipe connected therewith, said partition consisting of an invertedbell-shaped vertical portion whose lower open end is immersed in a liquid contained in a vessel, the vertical height of the said bellshaped portion being greater than the height of the barometric column of said liquid, the free surface of said liquid being in unrestricted communication with the said pipe, said bell-shaped portion having a float acting by buoyancy to raise the same from said liquid and break the seal at a predetermined diflerence of pressure between said vacuum vessel and said connecting pipe, and electromagnetic means for operating said seal.

6. An automatic vacuum valve for a vacuum Vessel comprising a tubular vertical chamber having a re-entrant tube at the bottom thereof, said tube communicating with said vacuum vessel, an inverted tubular bell enclosing said tube, a sealing liquid in the bottom of said chamber, a float in said sealing liquid, said float tending to support the lower end of said bell above the level of said liquid, and a connection from the space of said chamher around said bell to an exterior space against which said vessel is to be sealed whereby an increase of pressure in said space above a predetermined value causes said liquid to be displaced into the space between said tube and said bell to cause a decrease of the lifting effect of said float In testimony whereof I have signed my name to this specification.

MORITZ URICH. 

